On the Use of an ER-213 Detonator to Establish a Baseline for the ER-486

Dickson

2019

Proc. R. Soc. A.

An introduction to exploding bridge-wire (EBW) detonators is given followed by an extensive critical review of open source literature pertaining to these devices. The aim is to better establish the mechanism of operation. Some authors state that the key mechanism is shock-to-detonation while others maintain it is more thermal in nature, or a complex combination of both. In addition to EBW detonators, arc detonators and direct optical initiation detonators are also reviewed, and it is demonstrated that in this manner the usually coupled effects from both shock and deflagration can be somewhat decoupled. As a result, it is hypothesized that the mechanism of operation in all three detonators is in fact the same: the formation of a hot plasma with a power of ≈1 MW and emission in the ultraviolet drives a thermal explosion process.

Section: (B) Firesetsmentioning

confidence: 99%

Section: (B) the Magnitude Of A Shock From An Ebwmentioning

confidence: 99%

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A review of the mechanism by which exploding bridge-wire detonators function

Dickson

2019

Proc. R. Soc. A.

“…Although it has been shown that some of the ETT can be accounted for by the SDT buildup process (which presumably must be highly reproducible for a given particle SA and pressing density), there is still the matter of the ignition versus bridge-burst current or CDU charge voltage. Data from [42][43][44] process produced by the bridge-burst. It has been observed previously that the functioning of EBW detonators is not just a traditional SDT process [2].…”

Section: Explosive Powder Studiesmentioning

confidence: 99%

The effects of electrically exploding gold bridgewires into inert and explosive powder beds

Rettinger

2021

Shock Waves

The particle velocity created in beds of both low-density inert sugar and explosive PETN as a function of distance from an exploding bridgewire was measured using optical velocimetry and a silvered PMMA window. As expected, more violent bridge-bursts (from a greater-stored-energy capacitive discharge unit) resulted in greater particle velocities and a better supported compaction wave in sugar. In all cases, ramp waves, not shocks, were observed in the inert sugar. Large window velocities were observed for very powerful bursts (up to 270 m/s), but bursts required for stochastic detonator operation conditions resulted in sugar/PMMA window velocities of only 8–10 m/s 0.85 mm from the bridge location. In contrast, after a distance of only 0.65 mm, a building shock wave was observed in PETN under both threshold and reliable firing conditions. Subsequently a hot-spot-driven shock-to-detonation (SDT) process was observed prior to full detonation. The measured buildup process accounts for $$\approx $$ ≈ 66% of the so-called excess transit time (ETT) between the observed and theoretical total function time for the particular exploding-bridge-wire (EBW) detonator studied. The remainder must occur in the powerful output pellet region. In contrast to a common understanding, the ETT is found to be a weak function of the discharge energy. Thus, the operation of the detonator after a bridge-burst energy-to-powder reaction transition process is found to be hot-spot-driven SDT in both the low- and high-density pellets.

The action-integral and energy to explode short gold wires in ambient air

2021

Physics of Plasmas

This paper is about electrically induced explosions of short (1 mm) and thin (38 μm diameter) gold bridgewires in ambient air and contrasts this behavior with that observed for longer wires in a vacuum used in applications such as Z-pinch systems. The action-integral (the time integral of the wire current squared) and energy-to-burst are measured using high current discharge systems. It is found that in contrast to some reports, the action-integral to burst is not a constant for a specific wire geometry and material but, instead, is a function of the rate of current change in the wire around the time of burst and the related metric of the current flux at burst. Furthermore, it is found that the accuracy of the constant action-integral to burst approximation is dependent on the discharge system used. Short gold wires such as these have relevancy to exploding bridgewire detonators.